The present invention generally relates to perpendicular magnetization type magnetic heads which perform recording and reproduction by magnetizing a magnetic layer of a magnetic medium in a perpendicular direction, and more particularly to a perpendicular or vertical magnetization type magnetic head having a main magnetic pole and return a path magnetic pole or poles.
Generally, when performing recording and reproduction with respect to a magnetic recording medium by use of a magnetic head, the so-called longitudinal direction recording system is employed. According to the longitudinal direction recording system, a ring type magnetic head performs the recording by magnetizing a magnetic layer of the medium in the longitudinal or horizontal direction of the medium and the magnetic head performs the reproduction by scanning over the longitudinally magnetized magnetic layer of the medium. However, as the recording is performed with higher densities, the demagnetization force acting on the residual magnetism (remanence) becomes larger. There is a problem in that this demagnetization force introduces undesirable effects on the high density recording.
Accordingly, a perpendicular magnetization type head was proposed to eliminate the above undesirable effects. The perpendicular magnetization type head magnetizes the magnetic layer of the medium in the perpendicular direction (vertical or thickness direction) of the magnetic layer. According to this perpendicular magnetization type head, the recording density can be improved, and the demagnetization force is small. Theoretically, the demagnetization force does not act on the residual magnetism, and it is possible to satisfactorily perform the high density recording.
As one kind of the perpendicular magnetization type head, there is a proposed magnetic head comprising a main magnetic pole and an auxiliary magnetic pole disposed opposing the main magnetic pole. The magnetic medium is positioned between the main magnetic pole and the auxiliary magnetic pole of the magnetic head, and the magnetic layer of the magnetic medium is magnetized in the perpendicular direction thereof by the magnetic field which is generated between the main magnetic pole and the auxiliary magnetic pole. However, according to this magnetic head, it requires a troublesome operation of inserting the magnetic medium between the main magnetic pole and the auxiliary magnetic pole of the magnetic head. There is a disadvantage in that it is especially difficult to employ this magnetic head as a rotary head of a video signal recording and reproducing apparatus (so-called video tape recorder or VTR).
In order to overcome the disadvantages of the above proposed magnetic head, another perpendicular or vertical magnetization type magnetic head was proposed. This other proposed magnetic head comprises a main magnetic pole and return path magnetic poles, as will be described later on in the specification in conjunction with drawings. This other proposed magnetic head uses a magnetic tape having a high permeability layer formed on a base, and a perpendicular magnetization layer formed on top of the high permeability layer. According to this other proposed magnetic head, the thin main magnetic pole is sandwiched between a pair of non-magnetic members and a pair of ferromagnetic members, and the outer sides thereof are sandwiched by the return path magnetic poles which are made of a ferromagnetic material. In this other proposed magnetic head, a magnetic flux is formed through a magnetic path which starts from the main magnetic pole, perpendicularly passes the perpendicular magnetization layer of the magnetic tape, passes the high permeability layer in the longitudinal direction of the magnetic tape, and then returns to the main magnetic pole through the return path magnetic poles. The recording is thus performed by the residual magnetism which are formed perpendicularly in the perpendicular magnetization layer.
According to this other proposed magnetic head, the perpendicular magnetic recording of a desired signal in a desired signal band is performed by the main magnetic pole. However, spurious or false gaps are formed between the main magnetic pole and the edges of the return path magnetic poles, and there is a disadvantage in that unwanted signals having frequencies which are dependent of the width of the false gaps are also recorded inevitably. The unwanted signals which are recorded inevitably, are noise components with respect to the desired recording and reproducing signal. In a case where the desired recording and reproducing signal is a video signal, there is a disadvantage in that the above noise components are conspicuous in the reproduced picture.